Courtesy light for a boat



FIG. 1 is a front, right side perspective view of a courtesy light for a boat showing my new design, the left side being a mirror image of the right side;

FIG. 2 is a bottom plan view thereof, the top being a mirror image of the bottom;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a front elevational view thereof. 

The ornamental design for a courtesy light for a boat, as shown and described. 